Bisphenols are commonly used as monomers in the preparation of a wide variety of polymers, including polyethersulphones, polyetherketones, polyarylates, polyetherimides, polyphenylene oxides, epoxy resins and cyanate resins, cyanate ester resins and polycarbonates. Polycarbonates are a group of polymers that exhibit relatively high transparency, high ductility, high impact strength and low weight. These characteristics make polycarbonates suitable for a wide variety of products and uses, and particularly suitable for shatterproof windows, lightweight eyeglass lenses, other lenses such as vehicle headlamps and the like. The principal commercial polycarbonate is known as LEXAN (R) and is available from The General Electric Company of Stamford, Conn. This particular polycarbonate is also known as the polycarbonate of Bisphenol A because it is made from Bisphenol A and phosgene. Bisphenol A may be depicted by the following formula.

Notwithstanding the advantageous properties of polycarbonates made from Bisphenol A, it has been attempted to improve one or more of its properties, such as transparency, ductility, glass transition temperature and low weight. One prior monomer essentially added an additional aryl group to each side of the Bisphenol A monomer to reportedly increase the glass transition temperature while retaining the ductility of Bisphenol A polycarbonates. See U.S. Pat. Nos. 5,281,689 and 5,319,149 (“the '689 and '149 patents”). More specifically, the '689 and '149 patents disclose bis[4-(4′-hydroxyphenyl)-phenyl] alkanes of the formula:
where each R is independently a C1-4 primary alkyl or C6-10 cycloalkyl radical, with methyl radicals preferred. These monomers were limited to the specific spacer group disclosed, i.e., each R being a C1-4 primary alkyl or a C6-10 cycloalkyl radical, and to the symmetrical structure of two aryl units on each side of the specified spacer group. The limitations of the spacer group to the specific groups in turn limit the types of syntheses and applications of this monomer.
Another monomer reportedly used an oxygen atom as the spacer group between the two symmetrical biaryl units. A representative formula for this structure is as follows.

In summary, the prior bisphenol monomers generally were limited to 1) two symmetrical biaryl units separated by a limited number of specified spacer groups, namely a C1-4 primary alkyl, C6-10 cycloalkyl radical or an oxygen atom, and 2) two symmetrical aryl units separated by a spacer group. As such, the choice of monomers was limited, which limited the choice of starting materials and process to synthesize the desired monomers. The limited choice of monomers also limited the number and variety of polymers, derivatives, resins and other products that could be synthesized. Therefore, a need exists for improved bisphenol monomers and improved polymers made from bisphenol monomers.